1. Field of the Invention
The invention relates to a steering system.
2. Description of the Related Art
A steering column described in U.S. Patent Application No. 2009/0013817 (US 2009/0013817 A) includes an adjustment portion and a holding portion. The adjustment portion can adjust the position of the steering column. The holding portion does not move in an adjustment direction for the steering column in accordance with the positional adjustment of the steering column. The holding portion is provided with tooth portions disposed in the adjustment direction. A tooth plate that is an elastic body is penetrated by a clamp bolt that penetrates the adjustment portion and the holding portion. The tooth plate has tooth portions aligned in the adjustment direction.
Operating an operation member attached to the clamp bolt enables a pressing member through which the clamp bolt is inserted to be moved toward the holding portion. Moving the pressing member toward the holding portion allows the tooth plate to be pressed by the pressing member and moved toward the holding portion. At that time, the tooth portions of the tooth plate move into spaces between the tooth portions of the holding portion and mesh with the tooth portions of the tooth plate.
If the tooth portions of the tooth plate ride onto the tooth portions of the holding portion without moving into the spaces between the tooth portions of the holding portion, the pressing member presses the holding portion by deflecting the tooth plate. When a secondary collision causes the deflected tooth plate to move in the adjustment direction, the tooth plate returns to an original state in which the tooth plate is not deflected, and the tooth portions of the tooth plate move into the spaces between the tooth portions of the holding portion. Consequently, the tooth portions of the holding portion mesh with the tooth portions of the tooth plate.
In the steering column in US 2009/0013817 A, when a secondary collision occurs, the steering column acts to move in the adjustment direction with the tooth portions of the holding portion meshed with the tooth portions of the tooth plate, which is an example of a tooth member that moves in accordance with an operation of the operation member. Consequently, the tooth portions of the tooth plate are subjected to a force that acts in the adjustment direction from the tooth portions of the holding portion. Thus, the strength (shear strength) of the tooth portions of the tooth plate needs to be set so as to withstand shearing resulting from the force applied by the holding portion. However, since this tooth member is an elastic body, selection of a material for the tooth member is limited. This precludes an increase in the degree of freedom of design of the tooth member.